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Re: [PATCH v3] explicit_bzero yet again
- From: Zack Weinberg <zackw at panix dot com>
- To: Alexander Cherepanov <ch3root at openwall dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 11 Jan 2016 13:05:35 -0500
- Subject: Re: [PATCH v3] explicit_bzero yet again
- Authentication-results: sourceware.org; auth=none
- References: <564DE0BE dot 5070607 at panix dot com> <20151119155533 dot GT3818 at brightrain dot aerifal dot cx> <566593F4 dot 8040108 at panix dot com> <5693CB7D dot 5040909 at openwall dot com>
On Mon, Jan 11, 2016 at 10:34 AM, Alexander Cherepanov
<ch3root@openwall.com> wrote:
> On 2015-12-07 17:13, Zack Weinberg wrote:
>> However, presently no compiler will LTO-optimize across shared library
>> boundaries, and even if such a compiler existed I would argue that the
>> optimization you contemplate is invalid for functions whose semantics
>> are unknown to the compiler, because the library could be swapped out at
>> runtime.
>
> I see that you added some uses of explicit_bzero into glibc. Hence global
> optimization of glibc itself is a concern?
IIRC all those uses are in libcrypt rather than libc, but this is
still an excellent point which tips my personal opinion from "well,
ok, if it makes you happy" to "yes, we definitely need a barrier in
the implementation".
zw